Anaplastic large cell lymphoma with paraneoplastic neutrophilia: an association between IL-17 elevation and aggressive disease progression.

We report a case of anaplastic large cell lymphoma (ALCL) with involvement of bone marrow, exhibiting extreme leukocytosis leading to death due to multi-organ failure within 1 week after admission. The patient had a history of rheumatoid arthritis, and had severe pneumonia at admission. To elucidate the basis for the observed extreme neutrophilia, we analysed the levels of several cytokines in serum samples taken from the patient at diagnosis. The patient exhibited an extreme increase in interleukin-17 (IL-17), one of the major regulatory cytokines for inflammation and neutrophil migration. Interestingly, a recent study revealed that anaplastic lymphoma kinase (ALK)-positive ALCL cells produce IL-17. IL-17 also contributes to treatment resistance in multiple types of cancer. Given these previous findings, our case may suggest a possible link between overproduction of IL-17 and an aggressive ALCL phenotype. Further studies will be required to determine whether serum IL-17 levels serve as a useful prognostic marker for ALCL.